What common trait do hash functions share?

Hash functions are designed to convert input data of any size into a fixed-size string of characters, which is typically a hash value or digest. This fixed-size output is one of the defining characteristics of hash functions and allows them to provide a consistent size regardless of the size of the original input data. For example, regardless of whether the input is a single character or an entire book, the hash function will always generate a hash of the same length, making it efficient for storage and comparison.

Having a fixed-size output aids in various applications, such as data integrity verification, where a small hash value can replace larger sets of data in checksums and digital signatures. This ensures that any alteration of the input data can be quickly detected by comparing the new hash output to the original hash value.